Help with smoke simulation scaling and appending
You need to adjust the density for how much you scale the smoke. If the original scale was 1.0, the new density is:
$$
density' = density / scale
$$
If you want exactly same render result (from scaled camera closer/further from smoke), you will also need to adjust the Volume Sampling Step Size under Properties > Render Tab > Geometry:
$$
stepsize' = stepsize * scale
$$

The density can be adjusted by a driver from the material node tree. I added extra node, so the user still has the option to manually adjust:



The driver looks like this, I chose the Z axis as input:



The others can be locked from user input and their value copied from Z axis with drivers: